T cells are the central regulatory cells of the adaptive immune system. The regulation of their activation is of great importance in infectious disease, autoimmunity, and in the immune response against cancer. The immunological synapse is a well-defined structure at the interface between T cells and antigen presenting cells (APC), the cells that activate T cells in a tight cellular interaction. The formation of this structure has been related to efficient T cell activation. However, its function is still being debated. Here we propose a new approach to address the question of the function of the immunological synapse. We will determine whether the immunological synapse forms over a wide set of T cell activation conditions and then identify T cell signaling and effector functions that occur concommitantly. The establishment of a direct relation between synapse formation and a particular signaling or effector function will invoke the synapse as its mediator and vice versa. All experimental approaches and assays have already been established in the context of other applications, here we propose to apply them to the question of synapse function in a small self-contained project of substantial significance. [unreadable] [unreadable]